1. Field of the Invention
The present invention relates to an inkjet recording apparatus having a function of cleaning a nozzle plate provided in a recording head.
2. Description of the Related Art
Recent pervading inkjet printers simply/easily and inexpensively record images at a high speed. An inkjet printer generally carries a recording medium to face a recording head that ejects ink droplets. Then, when the recording medium is facing the recording head, the inkjet printer ejects ink droplets onto the recording medium from the recording head through nozzles. As a result, the inkjet printer records an image on the recording medium.
Nozzles of such an inkjet printer are formed on a nozzle plate. Dust, e.g., foreign particles or extraneous materials, a waste ink and others adhere to such a nozzle plate. When the inkjet printer records an image in a state where such dust or a waste ink has adhered to a part close to the nozzles of the nozzle plate, a discharging direction of ink droplets may change or ink droplets cannot be ejected in some cases. As a result, a quality of an image to be recorded may be possibly lowered. Thus, in the inkjet printer, the nozzle plate is generally conventionally cleaned. As a cleaning method, e.g., a mechanical wiping method and a cleansing method are known. According to the mechanical wiping method, for example, a wiper cleans off dust or a waste ink that has adhered to the nozzle plate, or an ink absorbing member, e.g., a sponge pressed against the nozzle plate sucks and removes dust or a waste ink that has adhered to the nozzle plate. Further, according to the cleansing method, a cap covers the nozzle plate, and discharges a cleaning liquid from the cap side to cleanse the nozzle plate.
However, in the mechanical wiping method, an ink-repellant coating layer (hereinafter, an ink-repellant coating) applied to the nozzle plate may be possibly abraded away to provoke an inconvenience in ink eject. Furthermore, when the nozzle plate is pressed by the wiper or the ink absorbing member, dust or a waste ink may possibly enter the nozzles to provoke clogging of the nozzles.
Moreover, in the cleansing method, a mechanism is complicated. Additionally, when a discharge pressure of the cleaning liquid is set large, the cleaning liquid may enter the recording head through the nozzles to be mixed with an ink.
In order to solve such problems, e.g., Jpn. Pat. Appln. KOKAI Publication No. 042678-1993 discloses a maintenance apparatus 100 for an inkjet printer. FIGS. 36A and 36B show a maintenance apparatus 100. An ink 102 pressurized by a pump (not shown) is supplied to a narrow tube 101 through an ink tube (not shown). A meniscus is formed on the narrow tube 101 by a surface tension of the ink 102. Further, when the pump applies a pressure, the ink 102 is formed into a bridge-like shape in a gap between a nozzle facet 103 of a recording head and the narrow tube 101 due to a capillary force. The ink 102 comes into contact with the nozzle facet 103. When application of a pressure by the pump is stopped in this state, the bridge-like ink 102 maintains the state where it is in contact with the nozzle facet 103, while the narrow tube 101 moves along the nozzle facet 103. As a result, the fine ink that has adhered to the nozzle facet 103 is absorbed into the bridge-like ink 102. When the narrow tube 101 moves away from the nozzle facet 103, the ink 102 is collected into the narrow tube 101, thereby effecting maintenance.
Furthermore, Jpn. Pat. Appln. KOKAI Publication No. 2002-283581 discloses a head wiping apparatus for an inkjet printer. A wiper group having three wipers is provided in this head wiping apparatus. In regard to length dimensions of the wipers, the length increases toward the rear wiper from the front wiper. The front wiper is not in contact with a nozzle plate of a recording head, and the two rear wipers come into contact with the nozzle plate of the recording head to perform cleaning.